THE ATMOSPHERE

1. THE ATMOSPHERE Learning Goal: Describe how the composition and structure of the atmosphere protects life on Earth. Essential Question: How does the composition and structure of the atmosphere protects life on Earth.

2. Main Ideas: • The atmosphere is divided into laters. • The atmosphere protects life from harmful radiation and regulates the planet’s temperature. • Weather is caused by changes in the atmosphere due to the transfer of energy in one form or another. • This energy transfer is driven by the solar radiation from the sun.

3. The Atmosphere • Atmosphere: the blanket of gasses that surrounds our planet held by gravity

4. The Early Atmosphere • Thought to be mostly water vapor and carbon dioxide. • Water vapor condensed and rained to fill the oceans. • The first organisms used carbon dioxide to perform photosynthesis which made oxygen.

5. Today’s Atmospheric Composition • 78% Nitrogen (N) • 21% Oxygen (O2) • 1% Other Gasses

6. The atmosphere also contains: • water vapor: which forms clouds and precipitation and absorbs heat energy • particles: like dust, salt, pollen • ozone: a gas in the ozone layer that absorbs harmful UV radiation. • Greenhouse gasses: gas molecules that absorb solar radiation, trap heat, and can increase the temperature of the atmosphere. • Carbon dioxide: most worrisome • Water vapor: most abundant

9. Atmospheric Layers • There are 5 layers of the atmosphere, divided by temperature. • Temperature is a measure of the average amount of kinetic energy of the particles in a material. (motion)

10. Layers from top to bottom: • Exosphere • Thermosphere • Mesosphere • Stratosphere • Troposphere

11. Exosphere (“Exo”- means outer) • outermost layer with no clear boundary • It extends into space

12. Thermosphere (“therm-” means heat) • Very little air here • Known for its great range of temperatures (-112⁰ F - 2000 ⁰ F) • Layer where space shuttles orbit • Produces the Aurora Borealis (Northern Lights)

13. Mesosphere (“Meso-” means middle) • Air is very thin • Temperature decreases. • Where meteors burn up and make shooting stars.

14. Stratosphere • Air is pretty thin • contains the “Ozone Layer” which is made of ozone gas that protects us from harmful UV radiation by absorbing it • This is why temperature in the stratosphere increases.

15. Troposphere • Bottom layer that contains most of the air. • Temperature decreases with altitude because the Earth’s surface warms it. • Where all weather occurs

16. Where all weather occurs. • The Sun heats the Earth through radiation. • The clouds block the sun during the day and keep heat in at night. • Water vapor and carbon dioxide also absorb heat and help keep it warm at night.

17. The ground absorbs the Sun’s radiation. • The ground heats the air above it through conduction. It gets cooler the farther away you get from the ground.

18. Convection TRIES to evenly distribute heat in the troposphere. • Warm, moist air rises, and cool air sinks and rushes in to replace it. This creates wind. • It is also how clouds form.

19. All three types of energy transfer happen in the troposphere.

20. Altitude is the height above sea level. • The higher you go, the less air there is.

21. Pressure is the weight of the air above you • The higher you go, the less air there is, so pressure decreases with altitude.